This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Malfunctions in intercellular communications can often lead to the formation of cancer cells or cell death in animals. In plants, intercellular communication mediated by plasmodesmata controls physiological and developmental processes by allowing macromolecular trafficking of proteins and various kinds of RNAs between cells. The focus of this project is to identify plasmodesmal channel proteins and to characterize their structure and function. Overall hypothesis underlying the proposed research is that plasmodesmal channel proteins are constituents of plasmodesmal channels, and that they therefore play crucial roles for both the architecture of and macromolecular transport through plasmodesmal channels. Our experimental goals aiming to test this hypothesis are: 1. Purify putative plasmodesmal channel proteins (PCP) by plasmodesmata enrichment, chromatographic, and immunological methods and determine their molecular identity by mass spectrometry analysis. 2. Characterize the structure and function of PCP and correlate domain information to the protein targeting and function. 3. Assess the role of PCP in macromolecular trafficking and cell-to-cell communication by analyzing loss- and gain-of-function mutants.